14 May 1991 T.I. (Tax Window, No. 3, p. 10, ¶1237)

Where a U.S. corporation sends its employees to a Canadian subsidiary for work assignments, and the employees report for work at the Canadian subsidiary but remain employees of the U.S. corporation, Regulation 100(4) will deem the employees to report for work at an establishment of the U.S. corporation outside Canada.

A U.S. corporation may be considered to be carrying on business in Canada where it supplies to its Canadian subsidiary employees that are under its direct control and supervision, in which case the provision of space to the employees at the Canadian subsidiary may constitute a place of business for purposes of Article V of the Canada-U.S. Convention.